1. Field of the Invention
The present invention relates to an image forming apparatus adopting an electrophotographic system such as a copy machine, FAX (facsimile machine) or a printer, and particularly to an image forming apparatus including an image forming apparatus body having a cartridge mount space in which a cartridge having a developer container is mounted, a cartridge which is loaded from the upper side of the image forming apparatus body and detachably mounted in the cartridge mount space, and a developer residual amount sensor which is supported so as to be pressed against the outer wall of the developer container of the cartridge when the cartridge is mounted in the cartridge mount space.
2. Description of the Related Art
According to the image forming apparatus of the above type, the developer residual amount sensor for detecting the residual amount of the developer in a developer container is used, and when the residual amount of the developer is reduced, it is displayed on a display of a user""s interface that the residual amount of the developer is small. According to the display content on the. display, the user carries out a cartridge exchange work.
The developer residual amount sensor described above is disposed so that the outer wall of the developer container is pressed against the developer residual amount detection face of the developer residual amount sensor when the cartridge having the developer container is loaded in the cartridge mount space of the image forming apparatus body. If the outer wall of the developer container and the developer residual amount detection face of the developer residual amount sensor are not brought into close contact with each other and thus a gap occurs between them, the detection sensitivity of the developer residual amount sensor is reduced and some detection miss occurs.
In order to bring the developer residual amount detection face in close contact with the outer wall of the developer container when the outer wall of the developer container is pressed against the developer residual amount detection face of the developer residual amount sensor, the developer residual amount sensor is required to be supported so that the developer residual amount detection face thereof can be freely inclined. Particularly in the case of a developer residual amount sensor using a magnetic sensor, the output of the developer residual amount sensor is varied due to minute variation in the distance between the outer wall of the developer container and the developer residual amount detection face, and thus xe2x80x9cclose contactxe2x80x9d is required (i.e., it is required that they are brought into close contact with each other).
The following technique on a developer residual amount sensor designed so that the developer residual amount detection face thereof can be inclined is well known.
According to the technique disclosed in Japanese Laid-Open Patent Application No. Hei-10-198154, a supported face of the developer residual amount sensor which is located at the opposite side of the cartridge confront face of the developer residual amount sensor on which the developer residual amount detection face is provided is supported by the tip of a pin so that the developer residual amount detection face can be inclined. In this technique, as the developer residual amount detection face is larger, the developer residual amount detection face is more liable to be inclined along the outer wall of the developer container, so that the developer residual amount detection face is more liable to come into close contact with the outer wall of the developer container. However, as the developer residual amount detection face is smaller, the developer residual mount detection face is less liable to be inclined along the outer wall of the developer container, so that the position of the developer residual amount sensor is unstable and thus erroneous detection is more liable to occur.
Accordingly, the present invention is directed to an image forming apparatus that substantially obviates one or more of the problems due to the limitations and disadvantages of the related art.
An object of the present invention is to provide an image forming apparatus including: an image forming apparatus body having a cartridge mount space in which a cartridge having a developer container filled with developer is detachably mounted; a sensor that detects a residual amount of the developer, the sensor being brought into contact with the outer wall of the developer container when the cartridge is mounted in the cartridge mount space; a holding member that fixedly holds the sensor; and a support member which rotatably supports the holding member so that the sensor is positionally variable so as to come into contact with the outer wall of the developer container.